Acrylonitrile Polymers, Survey and SAN

Abstract

Abstract Acrylonitrile has found its way into a great variety of polymeric compositions based on its polar nature and reactivity. Some of these areas include adhesives and binders, antioxidants, medicines, dyes, electrical insulations, emulsifying agents, graphic arts materials, insecticides, leather, paper, plasticizers, soil‐modifying agents, solvents, surface coatings, textile treatments, viscosity modifiers, azeotropic distillations, artificial organs, lubricants, asphalt additives, water‐soluble polymers, hollow spheres, cross‐linking agents, and catalyst treatments. Styrene–acrylonitrile (SAN) resins possess many physical properties desired for thermoplastic applications. They are characteristically hard, rigid, and dimensionally stable with load bearing capabilities. Modifiers may include uv stabilizers, flow and processing aids, and reinforcing agents. SAN resins show considerable resistance to solvents and are insoluble in carbon tetrachloride, ethyl alcohol, gasoline, and hydrocarbon solvents. Polar solvents such as acetone, chloroform, and pyridine will dissolve SAN. The properties of SAN are significantly altered by water absorption. Commercially, SAN is manufactured by three processes: emulsion, suspension, and continuous bulk. Acrylonitrile copolymerizes readily with many electron‐donor monomers other than styrene. Hundreds of acrylonitrile copolymers have been reported. Copolymers of acrylonitrile and methyl acrylate and terpolymers of acrylonitrile, styrene, and methyl methacrylate are used as barrier polymers. Environmentally degradable polymers are useful in packaging. The largest portion of SAN (80%) is incorporated into ABS resins, and their markets are inexorably joined. SAN resins themselves appear to pose few health problems, and they have been approved by the FDA for food packaging use.